The present invention relates generally to cameras, fluid speed governors and drive mechanisms and more particularly relates to panoramic cameras and speed governors and drive mechanisms for such instruments.
Photography which utilizes a slit in order to scan a panoramic view is believed to have been popularized initially in the 1850's. In any event, it is known that a slit camera was typically used at least as early as 1857 both for group photos and for scenic photography.
In about 1894, an apparatus was developed by M. Damoizeau of Paris for photographing a panorama extending throughout 360.degree.. In that camera, a lens was moved past an advancing film in a direction opposite to the direction of movement of the film. The lens was moved in the opposite direction at about the same speed that the film was advanced.
A slightly different arrangement for panoramic photography was developed in about 1901 by the Lumiere brothers. This apparatus also was able to photograph a panorama extending 360.degree.. In this arrangement, however, the film was held stationary while a lens and mirror arrangement rotated about the stationary film.
At the turn of the twentieth century, a large number of panoramic cameras were developed. During the First World War, a camera which was popularly known as the "Circuit Camera" was in widespread use. Also at about this time, panoramic cameras having an internal lens arrangement and stationary film were developed and used.
A wide angle lens was perfected for use in photography by about 1924 at which time a miniature 35 mm camera, commonly called the Leitz camera, became popular.
Soon afterwards, the panoramic camera became less popular and was only rarely used. It was not until the use of panoramic scan photography by military intelligence units during the Second World War that the panoramic camera was again used to any substantial extent. At that time, the panoramic photographs permitted the cross-reference and verification of information of maps.
During the early 1960's, interest in panoramic cameras was again aroused, especially among a small group of photographers. It was at this time that a number of new panoramic cameras were developed. The military also renewed interest in panoramic cameras which were found to be useful in high altitude equipment as recording instruments.
Numerous problems and disadvantages of panoramic cameras can be cited as contributing to the decline in interest in the panoramic camera from the time of the early 1900's. Conventional panoramic cameras are objectionable because of the occurrence of a series of vertical lines on the developed film as a result of uneven movement of the film. These vertical lines are referred to as "banding" and present one of the most difficult problems that occur in panoramic cameras. Each vertical line is typically caused by a very minor change in speed in the film which results in an underexposure of that portion of the film. This underexposure, however, is sufficient to result in the series of vertical white lines in the developed film.
Accordingly, it is an object of the present invention to provide a panoramic camera in which banding of the developed film is substantially reduced or eliminated particularly as a result of the elimination of gears and adjustments of the spacing of the slit with respect to the film.
Another objection to conventional panoramic cameras relates to the use of electric motors as drive mechanisms both for film advancement and for relative rotation of the main camera portion and handle. An electric motor including a gear cage and battery is typically expensive and constitutes a major portion of the cost of a camera. Furthermore, the electric motor and the other electrical portions of both panoramic and non-panoramic cameras are typically relatively unreliable in comparison with the non-electrical portions of the camera. For this reason, it is desirable to completely eliminate the electrical motor, gears and the battery systems of a camera.
Accordingly, a further object of the present invention is to provide a panoramic camera having a spring ribbon motor with a liquid rotor which obviates the need for an electric and gear drive mechanism.
Still another object of the present invention is to provide a panoramic camera having a high degree of reliability as a result of the substantial elimination of electrical circuitry and gearing.
The heretofore large size of the panoramic camera has resulted in another hindrance to the widespread use of panoramic cameras. The large size results in a camera which appears to be clumsy and awkward to the average consumer.
Therefore, yet still another object of the present invention is to provide a panoramic camera having a compact configuration whereby the physical size of the camera is substantially minimized.
The panoramic camera of the present invention includes a main camera portion and a handle which is rotatably attached to the main handle portion. A lens and slit arrangement is provided within the main camera portion for the continuous exposure of film. The film is crawl advanced within the camera with respect to the slit and lens arrangement. A drive mechanism which preferably includes a spring ribbon rotates the main camera portion with respect to the handle. The slit and lens arrangement is oriented radially with respect to a main axis of the panoramic camera so that rotation of the main camera portion permits the lens and slit arrangement to scan about the main axis. The spring ribbon of the main camera portion is wound in a reverse manner on a first spool and in a forward manner on a second spool with both spools having cam locks to limit the travel of the spring ribbon. A speed governor is provided in the handle to limit the speed of relative rotation between the main camera portion and the handle to a constant magnitude. The speed governor may include various arrangements and preferably includes a fluid and brush rotor mechanism. In preferred embodiments of the present invention the fluid may consist of a silicon oil, a hydrocarbon liquid having a high viscosity or one of a number of colloidal suspensions. A pulley and belt arrangement operatively connects the speed governor with the main camera portion. The film cassette and the film take-up spools are alternately driven by one-way roller clutches. Another one-way clutch in the speed governor allows the camera to automatically rewind the film.